Higher precision pitch marking for TD-PSOLA

The paper describes techniques to improve the precision of prosodic modifications with TD-PSOLA. TD-PSOLA relies on the pitch synchronous decomposition of the signal into overlapping frames synchronised with pitch period. The main objective is thus to preserve the consistency of marks between neighbouring frames with respect to the temporal structure of pitch periods. First, we improve pitch marking by eliminating mismatch errors which appear during rapid formant transitions. This is achieved by pruning pitch mark candidates whose distance with other candidates is clearly not consistent with the current pitch period. From the synthesis point of view we exploit a fast re-sampling method which allows signal frames to be shifted finely where they should appear given both the initial pitch mark and the location of pitch mark for synthesis. Together with the pitch marking improvement, this fast re-sampling method enables very high quality transformations characterised by the absence of noise between harmonics.